Add hub-core package, docs, and State Hub integration scaffold

Extract the first reusable slice (models, schemas, routers, MCP, migrations)
from state-hub with INTENT/SCOPE, agent instructions, workplan, and aligned
inter_hub capability registry index.

tests/test_utils.py

@@ -0,0 +1,45 @@
+import pytest
+from sqlalchemy import select
+
+from hub_core.models.domain import Domain
+from hub_core.utils import PageParams, apply_pagination, normalize_trailing_slash, resolve_repo_path, slugify
+
+
+class RepoStub:
+    local_path = "/fallback/path"
+    host_paths = {"workstation": "/host/path"}
+
+
+def test_slugify_normalizes_text() -> None:
+    assert slugify(" The Custodian: Hub Core! ") == "the-custodian-hub-core"
+
+
+def test_slugify_rejects_empty_slug() -> None:
+    with pytest.raises(ValueError, match="slug cannot be empty"):
+        slugify(" !!! ")
+
+
+def test_page_params_bounds() -> None:
+    assert PageParams(limit=10, offset=20).limit == 10
+    with pytest.raises(ValueError, match="limit"):
+        PageParams(limit=0)
+    with pytest.raises(ValueError, match="offset"):
+        PageParams(offset=-1)
+
+
+def test_apply_pagination_sets_limit_and_offset() -> None:
+    query = apply_pagination(select(Domain), PageParams(limit=25, offset=50))
+    compiled = str(query.compile(compile_kwargs={"literal_binds": True}))
+    assert "LIMIT 25" in compiled
+    assert "OFFSET 50" in compiled
+
+
+def test_resolve_repo_path_prefers_host_path() -> None:
+    repo = RepoStub()
+    assert resolve_repo_path(repo, "workstation") == "/host/path"
+    assert resolve_repo_path(repo, "unknown-host") == "/fallback/path"
+
+
+def test_normalize_trailing_slash_preserves_query_and_fragment() -> None:
+    assert normalize_trailing_slash("/repos?status=active#top") == "/repos/?status=active#top"
+    assert normalize_trailing_slash("/repos/?status=active", trailing=False) == "/repos?status=active"